Technically there's a few place that you can send to get it done.

Personally, I have never been to GH so will not comment, but I have sent my guitars to TGS Cheras and have them fixed it there. Sometimes its a good work, sometimes it isn't. But they're a rather friendlier lot.

Also have sent my guitars to John Lau Guitars. For John Lau, HIS (only him) services are good. He knows his stuff, but I can't speak for his staffs. There was a case where I sent my acoustic to lower the action and changing the saddle - however it didn't turned out well. On top of that the guitar was there for about 1 week, but came back with the neck concave and action very high.

So I DIY myself by filing the saddle and straighten the neck slowly.

In as much as every guitar service centre have their fall up, I think I'd still go with TGS and John Lau, but for John Lau I sure would want to make sure that its him that services the guitar and not his staffs.

John Lau Guitar : https://www.facebook.com/guitarservices

From Puchong its nearby.